The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Apr. 27, 2004
Filed:
Jan. 28, 2002
Marcus Pfeifer, Solingen, DE;
Barry Van Setten, Rodenbach, DE;
Jurgen Gieshoff, Biebergemund, DE;
Paul Spurk, Bad Konig, DE;
Egbert Lox, Hanau, DE;
Thomas Kreuzer, Karben, DE;
Umicore AG & Co. KG, Hanau-Wolfgang, DE;
Abstract
The present invention provides an exhaust gas treatment unit for an internal combustion engine. A first catalyst unit produces ammonia from corresponding constituents in a rich exhaust gas composition. A second catalyst unit that is located downstream of the first catalyst unit temporarily stores the ammonia produced by the first catalyst unit in the presence of a rich exhaust gas composition. In the presence of a lean exhaust gas composition, the nitrogen oxides present in the exhaust gas are subjected to a reduction reaction using the temporarily stored ammonia as reducing agent. The exhaust gas treatment unit also contains a third catalyst unit that is located between the other two catalyst units, and oxidizes the nitrogen oxides present in the exhaust gas at lean exhaust gas conditions to a such an extent that 25 to 75 vol. % of the nitrogen oxides entering the second catalyst unit consist of nitrogen dioxide.